Assassin
Well-Known Member
One other issue is that of battery life as they only quote battery function figures for a brand new battery and once its done some running with its charge and discharge cycles what is its capacity then.
Electric sportcruiser
- Thread starter GARYSJENKINS
- Start date
Bouba
Well-Known Member
True...but not true....large electric semis are already being built. Many corporations are very aware of their carbon footprint and how that looks to their customers...and they are seeking to reduce it...and transport is the area that they choose. For example...McDonalds advertise that their fleet of trucks run on chip fat (which of course they have an abundance)..other companies...for example Pepsi are going electric..a large corporation that takes loads from their depots to their plants to their distributors (in other words, all in house) can manage on battery power...and Pepsi has ordered a fleet of electric trucks.
So, while an independent trucker would struggle with the limitations of electric it can still be done and is being done.
The boat problem is cost and charging facilities....
gordmac
Well-Known Member
I am guessing the electric trucks will only move Pepsi a short distance to the warehouse and diesel ones will do the longer hauls to the retailers. That will be subcontracted so Pepsi can claim all their fleet are electric.
In cities where distances are short electric goods vehicles are feasible and should perhaps be compulsory (along with taxis and busses) to reduce city pollution.
Anywhere rural where vehicles have to do longer distances isn't practical. Another issue not seemingly mentioned is the capacity of the supply system. The energy loss in the cable is proportional to the current squared, this is why long distance transmission is at very high voltage. I suspect we will need a new high voltage supply network in most areas to cope with the high power demand for charging. The standard 230v won't do the job.
In cities where distances are short electric goods vehicles are feasible and should perhaps be compulsory (along with taxis and busses) to reduce city pollution.
Anywhere rural where vehicles have to do longer distances isn't practical. Another issue not seemingly mentioned is the capacity of the supply system. The energy loss in the cable is proportional to the current squared, this is why long distance transmission is at very high voltage. I suspect we will need a new high voltage supply network in most areas to cope with the high power demand for charging. The standard 230v won't do the job.
ontheplane
Well-Known Member
Electric will work for full displacement but for planing it's a non-starter.
I have an electric car, running at "normal" a-road speeds it will do 280m on a charge of its 64kw battery - but I run at perhaps 10-20% throttle 90% of the time. A boat runs around 60-70% of throttle to be on the plane - so a 200hp engine would eat a 64kwh battery in about 15 min.... And then take 9 hours to charge at 7kw.....
It just won't work with current batteries and current charging.
If you could get 1000kwh of battery in the boat keeping the weight realistic and have 350kwh chargers on every pontoon maybe - but you can't - imagine the draw on a Saturday if everyone had been out for 4 hours and wanted a re-charge. You'd need a Hinckley B at every marina.
I have an electric car, running at "normal" a-road speeds it will do 280m on a charge of its 64kw battery - but I run at perhaps 10-20% throttle 90% of the time. A boat runs around 60-70% of throttle to be on the plane - so a 200hp engine would eat a 64kwh battery in about 15 min.... And then take 9 hours to charge at 7kw.....
It just won't work with current batteries and current charging.
If you could get 1000kwh of battery in the boat keeping the weight realistic and have 350kwh chargers on every pontoon maybe - but you can't - imagine the draw on a Saturday if everyone had been out for 4 hours and wanted a re-charge. You'd need a Hinckley B at every marina.
gordmac
Well-Known Member
Maybe we will have a network of small reactors at marinas?
ontheplane
Well-Known Member
Even if that were possible - and marinas would be a good site for them, plenty of cooling, still doesn't fix the battery problem - to hold enough power for a planing boat batteries would be massive, and so heavy the boat wouldn't plane, needing bigger and heavier batteries and so on.
Until there is a quantum leap in batteries, won't work.
As I say, displacement - that's a totally different matter and completely viable
Until there is a quantum leap in batteries, won't work.
As I say, displacement - that's a totally different matter and completely viable
gordmac
Well-Known Member
Of course battery power is useless for traveling any sort of distance or speed but marinas have a lot of sail boats which could be battery powered if enough electricity was available. Hence my suggestion.
ontheplane
Well-Known Member
On boats this would be a non- issue
I charge my elec car every day and in 2 years battery SOH is still 100%, I still get the same range, the number of cycles on a boat would be tiny
KINGFISHER 9
Well-Known Member
No - they were advertised as having had the hybrid bit removed ... you'd have to assume they were inefficient or even useless! There must have been a good reason on what can't have been very old boats.
ontheplane
Well-Known Member
True, or even very efficient twin hull designs - with elec motors I would think 7-10 kts would be realistic and with solar panels a very low cost of cruising....
Lightwave395
Well-Known Member
My partners daughter has just gone to work for these guys, they've had a ton of venture money and are focuused more on City deliveries but isn't that where most of the pollution is ?
Can't wait for her to bring one home for the weekend !
Volta Trucks - Home
Can't wait for her to bring one home for the weekend !
Volta Trucks - Home
gordmac
Well-Known Member
Rough calculation: diesel about 56kj/l I think. Now 4l/h at 6kn seems reasonable from my limited displacement experience. That would be 224kj/h and 6' so 37kj/m. Say 35% efficiency and 100% for electric gives 13kj/mile needed. Seems a lot.
Bouba
Well-Known Member
Here’s a quick article that has done the maths for you...
About Electric Propulsion, Part 3: Battery Power for Your Electric-Boat Motor | BoatTEST
I think, for solar, it seems that a power cat is the best way forward, just for the roof size
About Electric Propulsion, Part 3: Battery Power for Your Electric-Boat Motor | BoatTEST
I think, for solar, it seems that a power cat is the best way forward, just for the roof size
ontheplane
Well-Known Member
On boats this would be a non- issue
I charge my elec car every day and in 2 years battery SOH is still 100%, I still get the same range, so with the tiny number of cycles on a boat, age would be the only problem - but it will certainly be 20 years of life and then a second use as home storage batteries probably.
Bouba
Well-Known Member
Which model is it ?
ontheplane
Well-Known Member
Not sure that is accurate.
Elec motors have stunning torque - so are perfect for displacement speeds.
I would think very small motors could easily power a displacement boat up to say 2/3rds of hull speed, but above that it all falls apart.
So in my EV I average 4.2m per KWH in Summer.... At motorway speeds that drops to 4.0 or even 3.9.
However - at town speeds I can get 15m per KWH - so electric motors are vastly more efficient at low speeds / low drag than ICE - however an ICE is efficient at higher speeds (most fuel cars are most efficient at motorway speeds - evs are most efficient at town speeds) hence why I think for canal, river and displacement boats elec can work - but planing, not yet
AndrewJ5
New Member
I am very sceptical about your 15 mile per kWh figure; in a 100kWh Tesla that would result in a range of 1500 miles; I’ve hypermiled in BEVs and not got near that high efficiency figure you quoted if we are talking about level ground; a gradient is another matter of course, but what comes up must go down and regen isn’t as efficient as not using the energy in the first place. EVs are at optimum efficiency between 20 and 25mph; any lower and you hold onto very little momentum, any higher and you get impacted by drag.
Bouba
Well-Known Member
I can get 500km or possibly more from a 75 kWh Tesla....that’s average driving at 137 Wh per kilometer....of course most people don’t drive like me
gordmac
Well-Known Member
As I said it seems high, perhaps someone can find where my estimates are wrong?
The power required to propel something is the force required (drag) X speed, not sure how your comment about torque fits with that. My estimate assumed 100% efficiency for electric. Maybe my diesel efficiency was a bit high.
I am not sure how the efficiency of an electric system varies with it's speed but your comment about ICE efficiency isn't correct. My thermodynamics is a bit rusty but peak efficiency will be at peak bmep which will be about peak torque I think.
gordmac
Well-Known Member
Unless I can't see a large part of that article it contains nothing helpful!